<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-04-09</periodOfReport>

    <issuer>
        <issuerCik>0001031927</issuerCik>
        <issuerName>Echo Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>ECTE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001248557</rptOwnerCik>
            <rptOwnerName>GRIECO WILLIAM</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>8 PENN CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>1628 JFK BLVD, SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>PHILADELPHIA</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-04-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>229000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares vest on April 9, 2014, provided, however that all unvested Restricted Shares shall immediately vest upon the sale of all or substantially all of the assets of the Company or all or substantially all of the outstanding capital stock of the Company in exchange for Liquid Proceeds. As used herein, &quot;Liquid Proceeds&quot; shall mean (a) cash; (b) securities which can be sold immediately on NYSE or NASDAQ; (c) securities which are or will be registered such that they can be sold upon on NYSE or NASDAQ upon termination of a lock-up period not to exceed one hundred eighty (180) days ; or (d) or a combination of cash and the foregoing securities</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kimberly A. Burke, Attorney-in-Fact</signatureName>
        <signatureDate>2013-04-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
